Lubricating oil



Patented May 24, 1949 LUBRICATING OIL Louis A. Mikeska, Westfield, N.J., asslgnor to Standard Oil Development Company, a corporation ofDelaware No Drawing. Application September 19, 1946, Serial No. 697,919

This invention relates to a mineral lubricating oil and moreparticularly to a new type of additive which imparts pour stabilizingproperties to such oil and improves other properties of the same.

This application is a continuation-in-part of my copending applicationSerial No. 653,152, filed March 8, 1946, (now Patent No. 2,443,264)which is a division of application Serial No. 523,091, filed February19, 1944 (now abandoned).

In accordance with the present invention a new class or organiccompositions are described which are useful as additives for minerallubricating oils, particularly those which are used in internalcombustion engines, in which they act as pour depressing and pourstabilizing agents, also as inhibitors of oxidation. I

The new class of additives have been found not only to be eflective insubstantially reducing the ASTM pour point of a lubricating oil, but instabilizing the pour point, thus providing a stable lubricating oilwhich will not solidify under conditions of fluctuating temperatureinvolved in normal outdoor conditions. The new additives of the presentinvention have been submitted to tests which simulate the normal varyingtemperature conditions encountered in winter field service, andsatisfactory results were obtained from their use, as will be explainedmore particularly hereinafter.

In serving as inhibitors of oil deterioration, the new additives aid inthe prevention of ring sticking, piston skirt varnish formation,deposition of sludge, and the like. They are particularly useful ininhibiting the normal corrosiveness of the oil when in contact withcopper-lead, cadmiumsilver and other similar bearings, now widely usedin automotive engines.

The new class of compounds which are employed as additives in accordancewith the present invention are organic compounds containing bothphosphorus and sulfur and may be considered as polysulfide derivativesof thiophosphoric and thiophosphorous acids, the latter being obtainedby reacting a sulfide of phosphorus with a mixture of a'.' wax-phenoland an aliphatic alcohol. It has been found that the reaction productderived from a mixtureof a wax-phenol and an alcohol is superior tosimilar products derived from wax-phenol or other alkylated phenolsalone in possessing superior oil solubility. It is believed that thepresence of the'alcohol prevents the formation of products of too highmolecular weight.

when the mixture of wax-phenol and alcohol is reacted with phosphoruspentasulflde, it is be- 9 Claims. (Cl. 260461) lieved that the reactionproceeds according to the following equation:

In the above equation R represents the waxphenol radical and/or thealiphatic radical from the alcohol, the equation representing astatistical average of reactions among the various molecules.Undoubtedly in many cases the thiophosphoric acid molecule will containboth the wax-phenol and the aliphatic radicals.

In forming the polysulfide derivatives of such thiophosphoric acid orthiophosphorous acid, the acid is treated with an oxidizing agent, e.g., iodine, potassium triiodide, ferric chloride, sodium hypochlorite,or oxygen itself, or with sulfur dichloride or sulfur monochloride, toform a disulfide, trisulfide or tetrasulfide, respectively, according tothe following equations:

The wax-phenols employed in accordance with the present invention may bederived in the usual manner by first chlorinating parafiln wax and thenreacting the latter with phenol. The aliphatic alcohols which areemployed in conjunction with such phenols may be any aliphatic alcohols,particularly suitable examples being methyl alcohol, ethyl alcohol,isopropyl alcohol, octyl alcohol, decyl alcohol, stearyl alcohol, oleylalcohol, and-the like. The mixture of wax-phenol and alcohol may bereacted with any of the sulfides of phosphorus, such as P233, P285,P483, P481, and the like.

The ratio of alcohol to phenol may be varied within wide limits. Thehigher the molecular weight of the wax phenol, the higher the ratio hasto be in order to obtain satisfactory oil solubility. Generally, apreferredratio is one to two wax-phenol hydroxyl groups to one moleculeof alcohol. v

In employing the additives: of the present invention for use either aspour depressants or as corrosion inhibitors, it has been found desirableto use thesame in the proportions of about 0.02% to 3%, preferably about0.1% to 2%, based on the lubricating oil'base stock.

In the following examples are illustrated methods for the preparation oftypical products of the present invention, andtests of the same withmineral lubricating oils. It is to be understood that these examples areillustrative only and are not to be considered as limiting the scope ofthe invention in any way.

Example 1.Preparation of substituted thiophosphoric acid A three-wayflask equipped with a stirrer and return condenser was charged with 51g. of waxphenol (prepared by heating 450 g. of chloroparaflln containing14% Cl with 90 g. phenol in the presence of AlCla), 15.8 g. decanol(decyl alcohol), 22.2 g. P285, and 150 cc. dioxane. (The amounts ofwax-phenol and decanol were calculated to provide 2 wax-phenol hydroxylgroups for each molecule of decanol.) The mixture was refluxed until nomore ms was given oil (about 2 hours). The reaction product was thendissolved in ether and transferred into a large beaker containing avolume of water approximately equal to the volume of the ether solution.Then while the mixture was rapidly stirred, a slight excess of hydratedlime was added. The mixture was stirred until the aqueous solutionremained permanently alkaline to litmus. The ether layer was thenseparated from the aqueous layer and the extract was dried over calciumchloride. The ether was; removed on a steam bath and the residue wastaken up with acetone. The small amount of undissolved material wasfiltered off and the acetone was removed at 100 C. under 2 mm. pressure.The product was obtained as a soft resin readily soluble in lubricatingoils.

Example 2.Preparation of the dtsulflde derivative A portion of thesubstituted thiophosphoric acid produced as described in Example 1 wassuspended in water and treated with an aqueous solution of potassiumtriiodide with vigorous shaking. When no more iodine was being absorbed,as could be seen from the brown color imparted to the aqueous layer, theaddition of the potassium triiodide was discontinued. Fi-, nally thereaction mixture was decolorized with sodium bisulfite solution. Thereaction product was then extracted with ether, washed with dilutesodium hydroxide solution and finally dried over sodium sulfate. Onremoval of the ether, a viscous reddish brown residue was obtained whichwas found to be readily soluble in lubricating oils.

Example 3.-Preparation of the trisulfide derivative A portion of thesubstituted thiophosphoric acid obtained in the preparation of Example 1was dissolved in an equal volume of dioxane and was treated with SCI; inthe ratio of one mol of SClz to 2 mols of the acid. The mixture was thenheated at 80 C. for about 2 hours, whereupon it was poured into waterand extracted with ether. The ether extract was then dried over sodiumsulfate. On removal of the ether the reaction product was obtained as aviscous brown oil, readily soluble in mineral oils.

Example 4.-Pour point and pour stability tests In these tests the ASTMpour point and the solid point as determined by the pour stability testdescribed below were measured, using various concentrations of disulfideand trisulfide products of Examples 2 and 3 in a waxy base minerallubricating oil consisting of an acidtreated Mid-Continent neutral oilwith the addition of il /2% of Pennsylvania bright stock, this oilhaving a viscosity of SAE 10 grade and a cloud point of +34 F,

Thepour stability of the various oil blends containing the new additiveswas determined by a test in which the temperature was varied to simulaterather severe winter temperature conditions. More specifically, thesamples were first gradually reduced in temperature from roomtemperature to +15 F. during the first day of the test, then warmedgradually to 45-50 F. during the second day, then held at about 35 F.for two days, these temperatures being close to the cloud points of the011 samples, and finally the tem- Additive Concentration Poul Stability(Solid Point), F.

ASTM Pour on Blend Point,

Base Oil Base 0il+Wax-phen01 Base OiH-Product of Ex.

It can be seen from the above data that although the wax-phenolsthemselves possess good pour reducing properties, the pour stability ofthe blend containing the same is very poor; while the disulfide andtrisulfide products of Examples 2 and 3 exhibit good pour stabilizingproperties as well as excellent pour depressing properties.

Example 5-Bearing corrosion test A test was made of the effect of thedisulflde product of Example 2 in reducing the corrosiveness of alubricating oil toward a copper-lead bearing, using a blend containing1% of the additive in a solvent extracted Mid-Continent parafllniclubricating oil of SAE 30 viscosity grade. A similar test was made ofthe unblended base. The test was conducted as follows: 500 cc. of theoil was placed in a glass oxidation tube (13 inches long and 2 inches indiameter) fitted at the bottom with a M; inch air inlet tube perforatedto facilitate air distribution. The oxidation tube was then immersed ina heating bath so that the'oil temperature was maintained at 325 F.during the test. Two quarter sections of automotive bearings ofcopper-lead alloy of known weight having a total area of 25 sq. cm. wereattached to opposite sides of a stainless steel rod which was thenimmersed in the test oil and rotated at 600 R. P. M. thus providingsufl'lcient agitation of the sample during the test. Air

. was then blown through the oil at the rate of Bearing Cor- Oil rosiouLife,

Hours Bus Oil 4 4 Base Oil-{4% Product of Ex. 2

'The products of the present invention may be employed not only inordinary hydrocarbon lubrieating oils but also in the "heavy duty typeof lubricating oils. which have been compounded with such detergent typeadditive as metal soaps, metal petroleum sulfonates, metal phenates,

metal alcoholates, metal alkyl phenol sulfides,

metal organo phosphates, thiophosphates, phosphites and thiophosphites,metal sallcylates, metal xanthates and thioxanthates, metal thioiliarysolvent agents may be used. The lubricating oils, however they may havebeen produced, may

vary considerably in viscosity and other properties depending upon theparticular use for which they are desired, but they usually range fromabout to 150 seconds Saybolt viscosity at 210 F. For the lubricating ofcertain low and medium speed Diesel engines the general practice hascarbamates, amines and amine derivaties, reaction products of metalphenates and sulfur, reaction products of metal phenates and phosphorussulfides, metal phenol sulfonates, and the like. Thus, the polysulfidederivatives of the organosubstituted thio acids of phosphorus may beused in lubricating oils containing such addition agents as bariumtert.-octyl phenol sulfide, calcium tert.-amyl phenol sulfide, nickeloleate, barium octadecylate, calcium phenyl stearate, zinc diisopropylsalicylate, alminum naphthenate, calcium cetyl phosphate, bariumdi-tert-amyl phenol sulfide, calcium petroleum sulfonate, zinc methylcycloheiwl thiophosphate, calcium dichlorostearate, etc.

The lubricating oil base stocks used in the compositions of thisinvention may be straight mineral lubricating oils or distillatesderived from parafiinic, naphthenic,asphaltic or mixed base crudes, or,if desired, various blended oils may be employed as well as residuals,particularly those from which asphaltic constituents have been carefullyremoved. The oils may be refined by conventional methods using acid,alkali and/or clay or other agents such as aluminum chloride, or theymay be extracted oils pro-. duced, for example, by solvent extractionwith solvents of the type of phenol, sulfur dioxide, furfural,dichlorodiethyl ether, nitrobenzene, crotonaldehyde, etc. oils maybeemployed as well as synthetic oils prepared, for example, by thepolymerization of olefins or by the reaction of oxides of carbon withhydrogen or by the hydrogenation of coal, or its products. In certaininstances cracking coil tar fractions and coal tar or shale oildistillates may also be used. Also, for special applications, animal,vegetable or fish oils or their hydrogenated or voltolized productsmaybe employed, either alone or in admixture with mineral oils.

For the best results the base'stock chosen should normally be that oilwhich without the new additives present gives the optimum performance inthe service contemplated. However, since one advantage of the additivesis that their use also makes feasible the employment of lesssatisfactory mineral oils or other oils, no strict rule can belaid downfor the choice of the base stock. Certain essentials must of course beobserved. The oil must possess the viscosity and volatilitycharacteristics known to be required for the service contemplated. Theoil must be a satisfactory solvent for the additive, although in somecases aux- Hydrogenated oils or white often been to use a lubricatingoil base stock prepared from naphthenic or aromatic crudes and having aSaybolt viscosity at 210 F. of 45 to seconds and a viscosity index of 0to 50. However, in certain types of Diesel service, particularly withhigh speed Diesel engines, and in aviation engine and other gasolineengine service, oils of higher viscosity index are often preferred, forexample, up to 75 to 100, or even higher, viscosity index. -In additionto the materials to be added according to the present invention, otheragents may also be used such as dyes, pour depressors, heat thickenedfatty oils, sulfurized fatty oils, organo metallic compounds, metallicor other soaps, sludge dispersers, antioxidants, thickeners, viscosityindex improvers, oiliness agents, resins,

' rubber, olefin polymers, voltolized fats, voltolized mineral oils,and/orvoltolized waxes and colloidal solids such as graphite or zincoxide, etc. Solvents and assisting agents, such as esters, ketones,alcohols, aldehydes, halogenated or nitrated compounds, and the like mayalso be employed.

Assisting agents which are particularly desirable are the higheralcohols having eight or more carbon atoms and preferably 12 to 20carbon atoms. The alcohols may be saturated straight and branched chainaliphatic alcohols such as octyl' alcohol (CaHuOH), lauryl alcohol(CHHZSOH), cetyl alcohol (CmHasOH), stearyl alcohol, sometimes referredto as octadecyl alcohol (ClBHIi'IOH), heptadecyl alcohol (CnHasOH), andthe like; the corresponding olefinic alcohols such as oleyl alcohol;cyclic alcohols, such as naphthenic alcohols; and aryl substituted alkylalcohols, for instance, phenyl octyl, alcohol, or octadecyl benzylalcohol or mixtures of these various alcohols, which'may be pure orsubstantially pure synthetic alcohols. One may also use mixed naturallyoccurring alcohols such as those found in wool fat (which isknown tocontain a substantial percentage of alcohols having about 16 to 18carbon atoms) and in sperm oil (which contains a high percentage ofcetyl alcohol) and although it is preferable to isolate the alcoholsfrom those materialsg-for some purposes, the wool fat, sperm oil orother natural products rich in alcohols may be used per se. Productsprepared synthetically by chemical processes may also be used, such asalcohols prepared by the oxidation of petroleum hydrocarbons, e. g.,paraflln wax, petrolatum, etc.

In addition to being employed in crankcase lubricants the additives ofthe present invention may also be used in extreme pressure lubricants,engine flushing oils, industrial oils, general machinery oils, processoils, rust preventive compositions and greases.

The present invention is not to be considered as limited by any of thesamples herein which are given by way of illustration only, but it is tobe limited solely by the terms of the appended claims.

I claim: I

1. As a new composition of matter the product obtained by reacting amixture of substantially equal molecular proportions of paraffinwax-phenol and decanol with a sufficient amount of phosphoruspentasulflde to convert the wax-phenol and decanol into dithiophosphoricacids and further reacting the product thus formed with potassiumtriiodide.

2. As a new composition of matter the product obtained by reacting amixture of substantially equal molecular proportions of paraflinwax-phenol and decanol with a sumcient amount of phosphorus pentasulfldeto convert the wax-phenol and decanol into dithiophosphoric acids andfurther reacting the product thus formed with sulfur dichloride.

3. As a new composition of matter the product obtained by reacting amixture of substantially equal molecular proportions of parafiinwax-phenol and decanol with a sufficient amount of phosphoruspentasulfide to convert the wax-phenol and decanol into dithiophosphoricacids and further reacting the product thus formed with sulfurmonochloride.

4. As a new composition of matter the product obtained by reacting amixture of parafiln waxphenol and an unsubstituted aliphatic monohydroxyalcohol containing 1 to 18 carbon atoms per molecule, such mixturehaving 1 to 2 waxphenol hydroxyl groups for each molecule of alcohol,with a sufficient amount of phosphorus pentasulfide to convert thephenol and alcohol present into dithiophosphoric acids, and furtherconverting the product thus formed with an oxi dizing agent selectedfrom the group which consists of potassium triiodide, sulfur dichloride,and sulfur monochloride capable of converting the same into apolysulfide.

5. As a new composition of matter the product obtained by (1) forming awax-phenol by condensing one molecular proportion of chlorinatedparaflin wax containing 14% chlorine with about one molecular proportionof phenol, (2) mixing the wax-phenol thus formed with decanol inproportions that will provide about two phenol hydroxyl groups for eachmolecule of decanol, (3)

reacting the mixture thus formed with a sufilhaving 1 to 2 wax-phenolhydroxyl groups for I each molecule of alcohol, with a suflicient amountof phosphorus pentasulfide to convert the phenol and alcohol presentinto dithiophosphoric acids. and further converting the product thusformed with an oxidizing agent selected from the group which consists ofpotassium triiodide, sulfur dichloride, and sulfur monochloride capableof converting the same into a polysulfide.

7. A method according to claim 6 in which the aliphatic alcohol isdecanol and in which the dithiophosphoric acids are converted into adisulfide product.

8. A method according to claim 6 in which the aliphatic alcohol isdecanol and in which the dithiophosphoric acids are converted into atrisulfide product.

9. A method of preparing an oil soluble additive for mineral lubricatingoils which comprises (1) forming a wax-phenol by condensing about onemolecular proportion of chlorinated paraflin wax containing 14% chlorinewith about one molecular proportion of phenol, (2) mixing the wax-phenolthus formed with decanol in propor tions which will provide about twowax-phenol hydroxyl groups for-each molecule of decanol, (3) reactingthe mixture thus formed in dioxane solution with phosphorus pentasulfidein sufficient amount to convert the wax-phenol and decanol intodithiophosphoric acids at the refluxing temperature of the mixture, and(4) reacting the dithiophosphoric acids formed in the previous step witha sufiicient amount of sulfur dichloride to convert the said acids intoa trisulfide derivative, the reaction being conducted in dioxanesolution at about C.

LOUIS A. MIKESKA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,763,851 Johnson June 17, 19301,763,852 Johnson June 17, 1930 1,867,631 Romieux et a1 July 19, 19321,889,943 Barsky et a1 Dec. 6, 1932 1,893,018 Christmann Jan. 3, 19331,949,629 Romieux et al Mar. 6, 1934 2,063,629 Salzberg et al. Dec. 8,1936 2,343,831 Osborne Mar. 7, 1944 2,362,624 Gaynor et al Nov. 14, 1944

